Methods for robotically inspecting gas turbine combustion components

ABSTRACT

A robotic inspection system for gas turbine combustion components includes an exterior manipulator for visual inspection of the exterior surface of the impingement sleeve, an interior manipulator for visual inspection of the interior of the transition piece body and an annulus manipulator for inspecting the side weld seams of the transition piece body. The exterior manipulator includes an arcuate segment extending about the annular spaced impingement sleeves and a robotic subassembly including a linear rail and an upper arm and forearm mounting an inspection head pivotally coupled to one another for visual inspection of the top, bottom and side external surfaces of the impingement sleeve. The interior manipulator mounts to the open end of the combustion casing and includes an arm mounted for universal pivotal movement to the mount, actuators for pivoting the arm and motors for extending and rotating an inspection head about pan and tilt axes within the interior of the transition piece body. The annulus manipulator includes a guide plate mounted to the combustor casing and having contoured surfaces tracking the side weld seams. A carriage mounts an inspection head and tracks along the contoured surfaces to track along the seam, affording remote visual inspection thereof.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a robotic inspection system forin situ inspection of gas turbine cannular combustion components for thepurpose of evaluating the condition of the components.

[0002] Maintenance costs and equipment availability are two of the mostimportant concerns of a gas turbine operator. Proper maintenance isrequired to minimize equipment downtime and provide long-term reliableoperation. Maintenance inspections of gas turbines are broadlyclassified as standby, running and disassembly. Disassembly inspectionsare generally categorized into three types: combustion inspection, hotgas path inspection and major inspection. All three types of inspectionsrequire shutdown and disassembly of the turbine to varying degrees toenable inspection and replacement of aged and worn components. Thecombustion inspection includes evaluation of several components of thecombustion system including the transition piece. The transition pieceis a thin-walled duct used to conduct high-temperature combustion gasesfrom the combustion chamber to the annular turbine nozzle passage. Thetransition piece and other combustion components are generally inspectedfor foreign objects, abnormal wear, cracking, thermal barrier coatingTBC condition, oxidation/corrosion/erosion, hot spots/burning, missinghardware and clearance limits. Components which fall outside establishedthreshold limits are replaced to maintain optimum operating conditionsfor the entire system. If not rectified, these conditions could lead toreduced machine efficiency and damage to the turbine that may result inunplanned outages and significant repair costs.

[0003] Removal and installation of transition pieces is the mosttime-intensive operation of the combustion inspection. This operationcontributes most significantly to the combustion inspection outageduration and corresponds directly to time lost producing power. Toremove transition pieces, all upstream components must be removed, i.e.,fuel nozzles, water injectors and various other hardware. Eachtransition piece is then dismounted and removed one by one in sequencethrough two access openings in the turbine casing. It will beappreciated that for certain gas turbines, there can be as many asfourteen transition pieces requiring removal.

[0004] To date, recommended practice has been to remove the transitionpieces and other combustion components to facilitate inspection andrefurbishment. Inspection has consisted primarily of visual methodsconsisting of the unaided eye with auxiliary lighting. Visual methods inknown problem areas have been enhanced with the use of liquid red dyepenetrant to improve visibility of small hairline cracking. Theseinspections have typically been performed offline of the combustioninspection process. Such prior inspection practices have manydisadvantages, including the time required for disassembly andinstallation, the lack of direct retrievable defect data for engineeringevaluation and historical comparison and complete reliance on humanfactors. Accordingly, there is a need for more efficient methods toinspect the transition pieces of the gas turbine combustion systems tominimize outage times while providing an accurate assessment of thecondition of each transition piece.

BRIEF SUMMARY OF THE INVENTION

[0005] In accordance with a preferred embodiment of the presentinvention, there is provided a robotic inspection system for gas turbinecombustion components comprised of three robotic manipulators withminiature cameras and lighting for inspecting various parts of thetransition piece of each combustor in situ. The manipulators are drivenremotely using a combination of automated and manual motion control toposition the inspection heads, e.g., video cameras, lighting and/ormeasuring devices, to various locations about and in the combustorenabling a detailed visual inspection of its transition piece and flowsleeve without disassembly and removal of these components from theturbine. The robotic inspection system hereof is thus intended for useduring a gas turbine maintenance outage.

[0006] Particularly, the robotic inspection system hereof includes threetools, i.e., an exterior manipulator, an interior manipulator and anannulus manipulator. It will be appreciated that the transition pieceincludes an outer impingement sleeve, typically perforated, and aninterior transition piece body defining generally an annulustherebetween. The forward ends of the transition piece body andimpingement sleeve are generally circular in configuration with top andbottom sides being flattened progressively toward the first-stagenozzle. The exterior manipulator is deployed for inspection of theexternal surfaces of the impingement sleeve and has seven distinctmotions. The exterior manipulator includes a segmented arcuate railmovably mounted on a carriage disposed within the casing of the turbine,the carriage being supported externally of the casing by a mast. Whenall of the arcuate rail segments are connected end-to-end to oneanother, the rail extends in excess of 90° such that an inspection headforming part of a robotic inspection subassembly carried on an endsegment can inspect top, bottom and side surfaces and along the entirelength of each impingement sleeve in a quadrant of the annularlyarranged combustors.

[0007] The robotic inspection subassembly on the end segment mounts agenerally axially extending rail on which is mounted an upper arm. Therail is movable in a circumferential direction with the arcuate segmentsas the latter are displaced circumferentially along the carriage tolocations radially outwardly of the impingement sleeves and within theinterior surface of the casing. The upper arm is pivotable relative tothe rail about a first axis to extend between adjacent impingementsleeves and carries at its distal end a pivotally mounted forearm. Theupper arm is also rotatable about its long axis such that when theforearm is extended, the inspection head carried at the distal end ofthe forearm can be located between and radially inwardly of animpingement sleeve for inspection of its radial inner surface. Theinspection head is rotatable about pan and tilt axes relative to theforearm and includes a vision module, e.g., one or more cameras and alighting system. With this arrangement, the inspection head can belocated to inspect the entire peripheral surface of each impingementsleeve of the cannular combustion system. A video micrometer external tothe tool may be used in conjunction with the vision module to effectmeasurements.

[0008] The interior manipulator is mounted to the aft combustion casingfor inspecting the interior surface of the transition piece body. Theinterior manipulator includes an elongated arm carried in a sphericalbearing in a mount secured to the casing flange. The interior end of thearm carries an inspection head similar to that of the exteriormanipulator. The arm projects through the mount exteriorly of the casingand is pivoted by two linear actuators coupled between the mount and thearm to locate the inspection head adjacent the interior surface of thetransition piece body. The arm also carries concentric inner and outertubes. Actuation of an electric motor carried by the outer tube extendsand retracts the inner tube carrying the inspection head. The inner tubecarries pan and tilt motors such that the inspection head can be rotatedabout pan and tilt axes for visual inspection of the interior surfacesof the transition piece body.

[0009] The annulus manipulator includes a manually positioned inspectionhead for inspecting the side seam welds along the exterior surface ofthe transition piece body in the annulus between the transition piecebody and the impingement sleeve. The annulus manipulator includes asupport structure for supporting a pair of spaced guide plates eachhaving a pair of contoured surfaces, e.g., grooves in opposition to oneanother. The grooves generally correspond to the contours of the sideseam welds of the transition piece body. A middle carriage plate carriessets of pins on opposite sides thereof engaging in the grooves and ismovable longitudinally along the guide plates. The middle carriage platealso carries side carriage plates for movement along respectivelaterally facing external surfaces of the guide plates. Each sidecarriage plate carries a holder for a wand tube which carries theinspection head. With the annulus manipulator located within the casingand the wand tube secured to one of the wand carriers, the side carriageplates are advanced toward the transition piece body by manuallyadvancing the wand tube. As the side carriage plates are advanced, theyfollow the contour of the grooves which enables the inspection head tofollow the contour of a side seam weld. Thus, by positioning theinspection head relative to the annulus manipulator, the inspection headcan be located directly adjacent a side seam weld of the transitionpiece body and displaced lengthwise along the transition piece bodythereby following and registering with the contour of the weld.

[0010] It will be appreciated that the cameras for the inspection headscan be remotely and dynamically focused from a remote control station.To accomplish this, motorized cam assemblies are utilized that move thecamera lens. Additionally, a video micrometer subsystem is used toquantitatively dimension features appearing in the video imagery. Forexample, a pair of laser lights at a fixed distance apart areincorporated into the inspection head of the interior roboticmanipulator. The lasers provide a known size feature used to calibratethe video micrometer for any camera field of view. A similar process maybe used for the exterior manipulator, although known size features ofthe transition piece body are used as the calibration reference ratherthan lasers.

[0011] In a preferred embodiment according to the present invention,there is provided a method of inspecting in situ an impingement sleeveof a combustor of an annular array of combustors in a gas turbinewherein the turbine has an outer casing about an axis of rotation of aturbine rotor and at least one opening through the casing for access tothe impingement sleeve, comprising the steps of inserting a roboticinspection tool carrying an inspection head through the opening in theouter casing, robotically manipulating the tool from a location externalof the casing to locate the inspection head between adjacent impingementsleeves, inspecting the exterior surface of one of the adjacentimpingement sleeves using the inspection head and after completion ofthe inspection, withdrawing the inspection tool from within the outercasing.

[0012] In a further preferred embodiment according to the presentinvention, there is provided a method of inspecting in situ an interiorof a transition piece body of one or more of a plurality of an annulararray of combustors for a gas turbine, comprising the steps of securinga mount of an interior robotic manipulator to an open end of acombustion casing forwardly of one of the transition piece bodies, themanipulator having an elongated inspection arm extending from the mount,locating an inspection head carried adjacent an end of the inspectionarm remote from the mount within the one transition piece body,manipulating the inspection arm to locate the inspection head adjacentinterior wall portions of the one transition piece body including bydisplacing the inspection head in a generally axial direction andgenerally radially toward a wall portion of the transition piece body tobe inspected.

[0013] In a still further preferred embodiment according to the presentinvention, there is provided a method of inspecting in situ side seamwelds along a transition piece body spaced inwardly of an impingementsleeve of a combustor in a combustion system for a gas turbine,comprising the steps of providing a guide having a contoured surfacegenerally corresponding to the contour of the side seam weld of thetransition piece body, fixing the guide to the combustor and displacingan inspection head longitudinally along the space between theimpingement sleeve and the transition piece body so that the inspectionhead tracks the contoured surface of the guide whereby the inspectionhead is maintained during its longitudinal displacement in registrationwith the side seam weld of the transition piece body.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a schematic illustration of an annular array ofcombustors about a gas turbine axis;

[0015]FIG. 2 is a fragmentary side elevational view of a combustor flowsleeve and a transition piece of a combustor illustrating an accessopening;

[0016]FIG. 3 is a schematic illustration of the movements of aninspection head of an exterior manipulator for inspecting exteriorportions of the impingement sleeve of the transition piece;

[0017]FIG. 4 is a perspective view illustrating an exterior manipulatorwithin the turbine casing adjacent an impingement sleeve;

[0018]FIG. 5 is a view similar to FIG. 4 with an upper arm and forearmof the exterior manipulator rotated and extended, respectively;

[0019]FIG. 6 is an axial end view of a segmented rail forming part ofthe exterior manipulator;

[0020]FIG. 7 is an enlarged view of a segment of the arcuate segmentedrail and a support carriage therefor;

[0021]FIG. 8 is an enlarged cross-sectional view of the carriage andsegment of FIG. 7 illustrating the drive therebetween;

[0022]FIG. 9 is a side elevational view in a plane containing the axisof rotation of the gas turbine rotor illustrating a rail mounting ashoulder gearbox, in turn mounting the upper arm and forearm of theexterior manipulator;

[0023]FIG. 10 is a plan view of the rail of FIG. 9;

[0024]FIG. 11 is an enlarged cross-sectional view of a gearbox carriedby the slider on the rail of FIGS. 9 and 10;

[0025]FIG. 12 is a cross-sectional view taken about on line 12-12 inFIG. 11;

[0026]FIG. 13 is a fragmentary view of the lower end of the upper arm,its joint with the forearm, the forearm and inspection head mounted onthe end of the forearm;

[0027]FIG. 14 is a view similar to FIG. 2 illustrating an interiormanipulator forming part of an inspection tool according to the presentinvention;

[0028]FIG. 15 is an enlarged cross-sectional view of the interiormanipulator of FIG. 14;

[0029]FIG. 16 is an end view of the mounting for the interiormanipulator with parts in cross-section;

[0030]FIG. 17 is an end elevational view of an annulus inspectionmanipulator according to the present invention;

[0031]FIG. 18 is a cross-sectional view of the annulus manipulator takenabout on line 18-18 in FIG. 17;

[0032]FIG. 19 is a side elevational view of the distal end of theannulus manipulator; and

[0033]FIG. 20 is a plan view of a wand tube forming part of the annulusinspection manipulator hereof.

DETAILED DESCRIPTION OF THE INVENTION

[0034] Referring now to the drawings, particularly to FIG. 1, there isschematically illustrated an axial view of a gas turbine, generallydesignated 10, having an outer casing 12 and an annular array ofcombustors including combustion flow sleeves 14 within the casing 12.The rotational axis of the gas turbine rotor, not shown, is indicated at16. Also illustrated in FIG. 1 is an access opening or manhole 18through which an external manipulator, generally designated 20, isinserted for inspecting the external surface of each of the impingementsleeves of the transition pieces. By manipulating the externalmanipulator 20, an inspection head 22 may be displaced axially the fulllength of the impingement sleeve as well as positioned at any locationabout the entire external peripheral surface of the impingement sleeve.

[0035] Referring now to FIG. 2, there is illustrated a flow sleeve 14and a transition piece 24, the transition piece including animpingement, i.e., perforated sleeve 26 surrounding a transition piecebody 28. Body 28 extends generally axially from adjacent the forward endof the impingement sleeve 26 and is connected at its rearward end to thefirst-stage nozzle, not shown, of the gas turbine for flowing hot gasesof combustion into the first-stage nozzle. The impingement sleeve 26 andtransition piece body 28 are generally circular at their forward endsand flatten out toward their rearward ends, terminating in a generallyrectilinear opening for flowing the gases into the first-stage nozzle.The surfaces of the impingement sleeve 26 and transition piece body 28generally conform with one another and are spaced one from the other,defining a generally annular space 30 between the surfaces of the sleeveand body. As noted previously, the combustion system component and moreparticularly the transition piece inspection system of the presentinvention includes three inspection tools, namely: an exteriormanipulator, an interior manipulator and an annulus tool. The exteriormanipulator is designed to inspect the external surface of theimpingement sleeve 26 for damage to the zipper welds, aft brackets andbullhorns. The interior manipulator is designed to inspect the insidesurface of the transition piece body 28 for cracking, corrosion and thelike and particularly for ensuring that the thermal barrier coating isintact. The annulus tool inspects the exterior surface of the side seamwelds 29 securing upper and lower halves of the transition piece body toone another.

[0036] Referring first to the exterior manipulator 20, and withreference to FIGS. 4-6, manipulator 20 is inserted in sections throughthe access opening 18 and includes a support carriage 32 connected to amast 34 secured externally of casing 12 to support the manipulator 20within the casing 12. The carriage 32, in turn, supports a plurality ofarcuate segments 36 connected one to the other and which segments extendalong an arc in excess of 90° in a plane perpendicular to the rotor axis16. It will be appreciated that access openings 18 are provided atlocations 180° apart about casing 12. Accordingly, by providing anexternal manipulator having segments 36 extending in assembly in excessof 90°, an inspection head at the end of the segments 36, and having twoaccess openings 18 at locations 180° apart, each of the impingementsleeves can be inspected by the inspection head in each quadrant aboutaxis 16 adjacent an access opening 18. The distal end of the arcuatesegments 36 carries a robotic inspection system subassembly, generallydesignated 39 (FIG. 6), including a rail 38 which extends in a generalaxial direction relative to the turbine rotor axis 16. Rail 38, in turn,carries a slider 40 (FIG. 10) mounting a shoulder gearbox 42 (FIGS. 11and 12). Projecting from gearbox 42 is an upper or first arm 44 (FIG.13) pivotally carrying a second arm, i.e., a forearm 46. At the distalend of forearm 46 is an inspection head 48 mounted for movement axiallyrelative to forearm 46 and in pan and tilt directions.

[0037] To facilitate an understanding of the movements of the externalmanipulator 20 prior to describing its component parts, the variousmotions of the external manipulator will be described with respect toFIG. 3. The rotational axis of the gas turbine is indicated 16 in FIG.3. The arcuate segments 36 lie in a plane perpendicular to axis 16. Therail 38 extends generally parallel to axis 16 and moves with the arcuatesegments 36 in a circumferential direction about axis 16 as indicated bythe double-ended arrow 50. The shoulder gearbox 42 mounted on slider 40moves with slider 40 in a generally axial direction along the rail 38,generally parallel to axis 16, thus displacing the upper arm 44, forearm46 and inspection head 48 in a forward and aft direction generallyparallel to axis 16. This linear movement of gearbox 42 is indicated bythe double-ended arrow 52 in FIG. 3. The shoulder gearbox 42 also causesrotation of the upper arm 44, forearm 46 and the inspection head 48carried at the distal end of forearm 46 about a generally tangentialfirst axis 53, the rotary motion about first axis 53 being indicated bythe arcuate double-ended arrow 54. Gearbox 42 also rotates the upper arm44 about its long axis 45 and which rotational movement about rotationalaxis 45 is indicated by the arcuate double-ended arrow 56. Forearm 46 ispivotally mounted to the distal end of upper arm 44 for rotation about asecond axis 57 extending through the elbow joint between the upper arm44 and the forearm 46 and perpendicular to a plane containing upper arm44 and forearm 46. The rotational direction is illustrated by thearcuate double-ended arrow 58 about axis 57 in FIG. 3. It will beappreciated that axes 53 and 57 are also parallel to one another.Inspection head 48 mounted on the distal end of forearm 46 is rotatablein pan and tilt directions. That is, inspection head 48 is rotatableabout the axis 59 of forearm 46 in pan and which rotation about axis 59is indicated by the arcuate double-ended arrow 60. Inspection head 48 isalso rotatable in tilt about an axis 61 perpendicular to the axis 59 offorearm 46 and which rotation about axis 61 is indicated by the arcuatedouble-ended arrow 62. Consequently, it will be appreciated that theinspection head 48 has seven degrees of freedom of movement.

[0038] Turning now to the details of the external manipulator 20 andreferring to FIGS. 6-8, it will be appreciated that the mast 34 (FIG. 6)is supported externally of casing 12 and is preferably fixed to thecasing. As illustrated in FIGS. 4 and 5 and to inspect the impingementsleeve, the carriage 32 is disposed within the casing 12 and supportedby mast 34. Referring to FIGS. 7 and 8, support carriage 32 includesspaced mounting plates 70 and a gear carriage 72 between plates 70. Gearcarriage 72 includes a centrally located spur gear 74 driven by theshaft 76 of an electric motor 78 carried within a housing 80 secured tothe support carriage 32. Plates 70 also carry rollers 82 at oppositeends of the carriage 32 for supporting the arcuate segments 36, as wellas side rollers 84 affording lateral support for the segments. Asillustrated in FIG. 8, each arcuate segment is in the form of an I-beam86 and includes a rack gear 88 along an upper surface of the segment. Itwill be appreciated that the engagement between motor-driven gear 74carried by the gear carriage 72 and rack 88 drives the arcuate segment36 along the carriage 32.

[0039] To facilitate insertion and removal of the arcuate segments, thegear carriage 72 is pivoted at one end about a pin 92. A spring-biasedshaft 94 biases the opposite end of the gear carriage 72 such that thegear 74 is biased into engagement with the rack gear 88. By displacingthe shaft 94 upwardly in FIG. 7, the gear 74 is disengaged from the rackgear 88, enabling the segments to freely slide on the rollers 82 alongthe carriage 32. Carriage 32 also includes a pair of cable guide wheels(FIG. 7) 90 for guiding electrical cables, not shown, along the arcuatesegments 36 for controlling the various motors of the externalmanipulator.

[0040] Referring now to FIG. 6, the ends of the arcuate segments 36 havedovetail connections one with the other. That is, each female dovetail83 may receive the male dovetail 85 of an adjoining segment such thatthe segments can be assembled within the casing 12. It will beappreciated that the distal end of the first inserted segment carriesthe robotic subassembly 39 including rail 38, shoulder gearbox 42, upperarm 44, forearm 46 and inspection tool 48. On the end of the distalsegment 36, a pin connection is provided to secure the distal segmentand the rail 38 to one another such that the rail 38 extends from thearcuate segment in a general axial direction (see FIGS. 3-5) and toopposite axial sides of the distal segment. The pin connection isillustrated in FIG. 10 by the female recess 96 and pin 97 coupled to asupport 99 secured to rail 38 intermediate opposite ends of the rail. Atthe distal end of rail 38 there is provided a gearbox 98 having a drivegear 100, an idler gear 101, and a driven gear 102. Gear 100 is drivendirectly by an electric motor 104 carried by rail 38. Drive gear 100drives driven gear 102 through the idler gear 101. Mounted on gear 102is a lead screw 108 extending the length of rail 38. A nut, not shown,fixed to the slider 40, is threaded about the lead screw 108. The slider40 is mounted on rail 38 by rollers whereby the slider 40 traverses thelength of rail 38 upon rotation of the lead screw 108.

[0041] Referring to FIGS. 11 and 12, the shaft 120 of the shouldergearbox 42 is keyed and secured to the slider 40 at the projecting end121, i.e., the shaft 120 does not rotate relative to slider 40.Consequently, the shaft 120 and shoulder gearbox 42 translate withslider 40 linearly along the rail 38 upon rotation of lead screw 108.The gearbox 42, however, rotates about shaft 120. To accomplish this, agear 122 is rigidly mounted on the shaft 120, i.e., the shaft 120, gear122 and slider 40 are rigidly connected with one another. A motor 124 ismounted on gearbox 42 and drives a gear 126 in engagement with gear 122.Since gear 122 is fixed to shaft 120, actuation of drive motor 124rotates gears 126 and 122, causing the gearbox 42 to rotate about shaft120, i.e., first axis 53 (FIG. 3).

[0042] Additionally, the shoulder gearbox includes a motor 150 (FIG. 11)for rotating the upper arm 44. The upper arm 44 is mounted on a bearing152 surrounding a fixed stub shaft 154 coupled to the housing of thegear box 42. A thrust bearing 156 carries the upper arm 44 for rotation.A gear 158 is connected to the outer tube 160 of the upper arm 44 andengages a gear 162 on the shaft 164 of motor 150. Consequently, byactuating motor 150 in either direction, the gear drive rotates theupper arm 44 about its own axis, i.e., rotational axis 45 (FIGS. 3 and11).

[0043] Referring to FIG. 13, the forearm 46 is secured to the distal endof the upper arm 44 for pivotal movement about the second axis 57 (FIGS.13 and 3). Particularly, upper arm 44 carries a bearing sleeve 180 (FIG.13) surrounded by a bushing 182 carried by the forearm 46. A drivepulley 184 is carried on the bushing 182 and cables 186 are wrappedabout pulley 184 for pivoting the forearm 46 about axis 57 and relativeto the upper arm 44. Particularly, cables 186 are wrapped about a cabledrum 187 (FIGS. 11 and 12) and extend past idler rolls 185 (FIG. 11),through an interior guide tube 188, about idler rolls 189 and aboutdrive pulley 184. To pivot the forearm 46 relative to the upper arm, adrive motor 191 (indicated by the dashed lines in FIG. 12) is mounted togearbox 42 and has a drive shaft 193 carrying a gear 195. Gear 195engages a gear 197 mounted for rotation on shaft 120. Gear 197 iscoupled to cable drum 187. By actuating motor 191, the cable drum isrotated, driving the cables 186 and hence pivoting forearm 46 relativeto upper arm 44 above second axis 57.

[0044] The forearm 46 preferably includes an outer tube 190 (FIG. 13) towhich is fixed a pan motor 192 internally within tube 190. The shaft 194driven by motor 192 is connected to the proximal end of an interiorrotatable tube 196 concentric within outer tube 190. The distal end oftube 196 is connected to the inspection head 48. Thus, actuation ofmotor 192 rotates inspection head 48 about the long axis of forearm 46,i.e., about a pan axis 59 (FIGS. 3 and 13).

[0045] Within inner tube 196 is a tilt drive motor 198 which drives ashaft 200, in turn coupled to a bevel gear 202. The shaft 200 is mountedin a bearing 204, the outer race of which is carried by inner tube 196.Bevel gear 202 lies in meshing engagement with a driven bevel gear 204mounted on a tilt axis shaft 206, suitable bearings being provided forthe shaft 206. Actuation of motor 198 thus rotates inspection head 48about the axis of shaft 206, i.e., about tilt axis 61 (FIGS. 3 and 13).The inspection head 48 includes various instruments such as a camera 208and a light assembly 210, both mounted on the shaft 206. Consequently,actuation of tilt motor 198 rotates the camera and light assembly aboutthe tilt axis to the desired positions.

[0046] In operation, the exterior manipulator carriage 32 is disposed inthe access opening 18 of the gas turbine and secured by securing themast 34 to the casing 12. The first arcuate segment carrying the rail38, gearbox 42, upper arm 44, forearm 46 and head 48 is inserted throughthe access opening and along carriage 32. The carriage 32 supports theassembly within the casing 12. The remaining arcuate segments 36 areconnected to one another end-to-end by the dovetail connections andpassed through carriage 32. With the upper arm 34 and forearm 46 foldedagainst one another in a retracted position paralleling rail 38 andretracted along the rail to the proximal end thereof directly adjacentthe end arcuate segment 36 as illustrated in FIG. 4, the inspection head48 can be advanced about a quadrant of the combustion casing and in acircumferential direction by actuation of motor 78 until it liesadjacent the impingement sleeve sought to be inspected. That is, thesubassembly 39 is advanced in a circumferential direction in the radialspace between the impingement sleeve 26 and the interior of casing 12until it lies adjacent the impingement sleeve to be inspected. With themanipulator in the position illustrated in FIG. 4 between adjacenttransition pieces and radially outwardly thereof, the upper arm 44 canbe rotated and forearm 46 displaced from its folded position againstupper arm 44 into positions to locate the inspection head 48 adjacentthe area of the transition piece, i.e., impingement sleeve 26, to beinspected. For example, if the area to be inspected is to one side ofthe impingement sleeve, the drive motor 124 in the shoulder gearbox 42is energized to rotate the shoulder gearbox 42 about shaft 120, i.e.,axis 53. Additionally, the cable drum 126 is rotated by actuation of themotor 191 to pivot the forearm 46 relative to the upper arm 44 aboutaxis 57 into the position illustrated in FIG. 5. Motor 104 is alsoactuated and displaces the shoulder gearbox 42 linearly along the rail38. By translating the gearbox 42 along the rail 38, the axial positionof the inspection head 48 in relation to the area desired to beinspected is obtained. Actuation of pan and tilt motors 192 and 198,respectively, position the inspection head 48 and particularly thecamera and light assembly in registration with the desired inspectionarea. Consequently, visual inspection by video camera and measurementsof the desired area are obtained. In the event the underside of theimpingement sleeve is to be inspected, the shoulder gearbox 42 isrotated about axis 53 to locate the elbow, i.e., the joint between upperarm 44 and forearm 46 below, i.e., radially inwardly of, the impingementsleeve. Motor 191 is also actuated to rotate the forearm 46 about axis57 to locate it below, i.e., radially inwardly of the impingementsleeve. Motor 150 is also actuated to rotate the upper arm 44 about itsown axis 45, thus causing the forearm 46 to swing about the axis ofupper arm 44 and below the impingement sleeve. By actuation of the panand tilt motors 192 and 198, the camera and light assembly can befocused on the area sought to be inspected. Thus, it will be appreciatedthat by selective actuation of the various motors and positioning theexterior manipulator on opposite sides of the selected impingementsleeve, the entirety of the exterior surface of each of the impingementsleeves for each combustor can be visually inspected and measurementstaken in situ. Note that the motors are all electrically driven remotelyfrom outside the turbine casing through suitable electrical connectionstherewith. The motors can be actuated manually but are preferablycomputer controlled.

[0047] Referring now to FIGS. 14, 15 and 16, there is illustrated aninterior manipulator, generally designated 200, for inspecting theinterior surface of the transition piece body 28. Referring to FIG. 14,the interior manipulator 200 includes a mount 202 at one end of the tooland an inspection head 204 at the opposite end of the tool carrying, forexample, a similar camera and light assembly as the exteriormanipulator. The mount 202 is in the form of a cross (FIG. 16) havinglegs 206 90° from one another. The legs 206 are mounted to the flangesof the combustion casing to secure the interior manipulator thereto. Thecentral portion 208 of the mount 202 includes a spherical bearing 210carried on a tubular section 212 projecting outwardly of the mount 202.On the inside of the mount 202 and carried by the tubular section 212 isan outer tube 214 for carrying the inspection head 204.

[0048] In order to manipulate the inspection head 216 within thetransition piece body 28, a pair of linear actuators 220 are coupledbetween the outer ends of a pair of legs 206, respectively, and theouter end of the tubular section 212. Particularly, each linear actuator220 is pivotally secured to a clevis 222 mounted to the outer end of aleg 206. The actuator 220 includes a motor 224 which drives a lead screw226 engaged in a threaded nut 228 mounted on a hinge 230. The hinge 230is, in turn, mounted on the tubular section 212. By locating the linearactuators 220 90° apart, it will be appreciated that actuation of themotors 224 pivots the inspection head 216 about the spherical bearing210 toward and away from the transition piece body 28.

[0049] Additionally, by extending or retracting the inspection head 204,the inspection head can be located adjacent any interior surface portionof the transition piece body 28. To accomplish the telescoping movement,a motor 232 is carried by the tubular section 212. Motor 232 drives alead screw 234 via a shaft coupling 236. A lead screw nut 238 is securedto an inner tube 240 concentric with outer tube 214. By actuating motor232 and rotating lead screw 234 in engagement with nut 238, tube 240,which mounts the inspection head 204, can be advanced and retracted inan axial direction.

[0050] To rotate the inspection head 204 about its own axis, i.e., topan the inspection head, a pan motor 242 drives a shaft 244, in turncoupled to a tube 246 carrying the inspection head 204. Thus, byactuating motor 242 and rotating shaft 244, tube 246 and head 204 arerotated about the axis of the outer tube 214. To rotate the inspectionhead 204 about a tilt axis 248, a tilt motor 250 is provided and drivesthe inspection head about axis 248 through a shaft and beveled gearconnection 250 and 252, respectively, similarly as previously describedwith respect to the exterior manipulator. It will be appreciated thatthe section 212 and tubes, i.e., members 214, 240 and 246 arecollectively called the inspection arm.

[0051] The operation of the interior manipulator is believedself-evident from the foregoing description. Upon securing mount 202 ofthe interior manipulator to the flange of the combustor, actuation ofthe linear motors 224 and 232 locate the inspection head 204 closelyadjacent to a selected interior surface portion of the transition piecebody sought to be inspected. By actuating motors 242 and 250, theinspection head is rotated about pan and tilt axes and directed suchthat the light assembly illuminates the surface portion to be inspectedby the video camera of head 204.

[0052] Referring now to the annulus manipulator illustrated in FIGS.17-20, the inspection head which preferably carries a camera and a lightassembly similar to the previously described inspection heads ispositioned in the annulus 30 between the transition piece body 28 andthe impingement sleeve 26. The annulus manipulator is specificallyconfigured to inspect the side seam weld 29 along opposite sides of thetransition piece body. It will be appreciated the transition piece body28 is fabricated in upper and lower halves, with the halves being weldedtogether along weld lines 29 which essentially follow the contour of theshaped upper and lower exterior surfaces of the transition piece body28. To inspect those welds 29, the annulus manipulator, generallydesignated 300, includes a pair of mounting plates 302 which are securedby bolts during inspection to the flanges of the combustor casing.Between the mounting legs 302, there is provided a pair of spacedV-rails 304. Extending centrally between the rails 304 is a lead screw306, terminating at one end in a manually rotatable knob 308 supportedby one of the mounting plates 302. The opposite end of the lead screw306 is journalled into the opposing mounting plate 302. Lead screw 306extends through a lead nut block 310, secured between and to a pair ofspaced guide plates 314. The guide plates 314 are secured to one anotherby suitable spacers at longitudinally located positions along thelengths of the plates and serve as a guide for guiding an inspectionhead 347 along the side seam weld 29. Additionally, rollers 316 areprovided on the outside of the guide plates 314 for bearing against therails 304 to maintain the plates 314 in extended positions from themounting plates 302 as illustrated in FIG. 18. By operation of the knob308, the guide plates 314 can be displaced accurately toward and awayfrom opposite sides of the transition piece upon insertion of theannulus manipulator into the transition piece.

[0053] As best illustrated in FIG. 18, each of the guide plates 314includes a pair of longitudinally extending contoured surfaces, i.e.,grooves 320 and 322. The grooves of each plate 314 register withcorresponding grooves of the opposite plate. Disposed between the guideplates 314 is a middle carriage plate 324 which carries a pair of guidepins 326 projecting from each of its opposite sides and engaging in thegrooves 320 and 322, respectively. It will be appreciated that themiddle carriage plate 324 is slidable lengthwise along the spaced guideplates 314 and along the grooves 320 and 322 of the guide plates 314,the middle carriage plate 324 serving as a cam follower with respect tothe contoured surfaces 320 and 322. Opposite ends of the middle carriageplate 324 mount transversely extending end carriage plates 328. Alongthe outside side faces of the guide plates 314 are side carriage plates330 (FIG. 19) which extend between the outer edges of the end carriageplates 328. Thus, the middle carriage plate 324 and end carriage plates328 form essentially an I-beam with the side carriage plates 330extending parallel to the middle carriage plate 324 and between endedges of the end carriage plates 328 along outside surfaces of the guideplates 314.

[0054] On each of the exterior surfaces of the side carriage plates 330,there is provided an arm 332 pivotal about a pin 334. Each side carriageplate 330 mounts a pair of bearings 336 through which a lead screw 338is rotatable. Lead screw 338 is rotatable on a nut 340 pivotally carriedon the upper end of arm 332. Nut 340 is also movable vertically relativeto its mounting 341 on arm 332. By rotating the lead screw, the nut 340causes the arm 332 to pivot about pin 334 to provide a finite adjustableangular movement of the inspection head, as described below.

[0055] On each side of each side carriage plate 330, there is provided amounting block 344 (FIGS. 17 and 19). A wand holder 346 is pinned to oneof the mounting blocks 344. The lateral outer end of the wand holder 346is adapted to receive a wand tube 348, illustrated in FIG. 20, on theend of which is mounted an inspection head 347. Head 347 includes alight assembly 349 and a video camera 351.

[0056] A carriage handle 348 is coupled by a universal joint 350 withthe lead screw 338, the handle 348 extending the length of the annulusmanipulator for manipulation externally thereof. By rotating thecarriage handle 348, the arm 332 carrying the wand tube 348 in the wandholder 346 can be pivoted to finitely locate the inspection head 347along the weld seam 29.

[0057] In using the annulus manipulator, the mount 302 is secured to theflange of the combustion casing, with the middle and side carriageplates 324 and 330, respectively, extending into the transition piece,terminating short of the transition piece body 28. The wand tube 353with the inspection head 347 is mounted to the wand holder 346 extendsthe length of the annulus manipulator. The middle and side carriageplates are jointly advanced along the guide plates 314 by pushing on thecarriage handle 348. The inspection head 347 is thus guided into thespace between the transition piece body 28 and the impingement sleeve26. As the inspection head 347 is advanced into the annulus, the sidecarriage plates 330 are guided by the movement of the middle carriageplate 324 along the grooves 320 and 322 to follow the contour of theside seam weld 29. With the inspection head mounted on one of the sidecarriage plates 330, the inspection head likewise follows the contour ofthe side seam weld 29. The video camera and light assembly forming partof inspection head 347 thus register with the side weld 29 and recordthe integrity of the side seam weld. By threading or unthreading thelead screw 338, the angle of the camera 351 and light assembly 349 canbe finitely adjusted within the annulus to view appropriate areas oneither side of the weld seam and/or to ensure registration of the cameraand light assembly with the weld. After the inspection of one side weldseam, the annulus manipulator is retracted and the wand carrying theinspection head 347 is secured to the mounting block 344 carried by theother side carriage plate 330. The plates 324 and 330 are then advancedfollowing the contours of the grooves 320 and 322 whereby the inspectionhead traverses along and inspects the opposite side weld seam.

[0058] While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiment, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. A method of inspecting in situ an impingementsleeve of a combustor of an annular array of combustors in a gas turbinewherein the turbine has an outer casing about an axis of rotation of aturbine rotor and at least one opening through said casing for access tothe impingement sleeve, comprising the steps of: inserting a roboticinspection tool carrying an inspection head through the opening in theouter casing; robotically manipulating said tool from a locationexternal of said casing to locate the inspection head between adjacentimpingement sleeves; inspecting the exterior surface of one of saidadjacent impingement sleeves using the inspection head; and aftercompletion of the inspection, withdrawing the inspection tool fromwithin the outer casing.
 2. A method according to claim 1 wherein thestep of manipulating includes displacing said inspection head ingenerally circumferential and radial directions to locate the headbetween said adjacent impingement sleeves.
 3. A method according toclaim 1 wherein the step of manipulating includes displacing saidinspection head in a generally circumferential direction to move past afirst impingement sleeve radially outwardly thereof and subsequentlydisplacing said inspection head radially inwardly between said adjacentimpingement sleeves.
 4. A method according to claim 1 wherein the stepof manipulating includes pivoting said inspection head about an axisgenerally perpendicular to the axis of rotation of the rotor and in aplane generally normal to the axis of rotation of the rotor.
 5. A methodaccording to claim 1 wherein the step of manipulating includesdisplacing said head toward said one impingement sleeve and away from animpingement sleeve adjacent said one impingement sleeve.
 6. A methodaccording to claim 1 wherein the step of manipulating includestranslating said inspection head in a direction generally parallel tosaid axis of rotation of the rotor and toward a first-stage nozzle ofthe turbine.
 7. A method according to claim 1 including manipulatingsaid inspection head to locate said inspection head radially inwardly ofsaid one impingement sleeve.
 8. A method according to claim 1 whereinthe step of manipulating includes translating said inspection head in adirection generally parallel to the axis of rotation of the turbinerotor, rotating said inspection head in a direction generally toward theaxis of rotation of the rotor and rotating said inspection head about agenerally radial axis.
 9. A method according to claim 1 wherein saidtool includes an arcuate arm about the axis of the turbine rotor, a railcoupled to said arm and extending in a generally axial direction, anupper arm translatable along said rail, and a forearm pivotally coupledto said upper arm and carrying the inspection head adjacent a distal endthereof, including the steps of translating the upper arm and forearmcoupled thereto along said rail, pivoting the upper arm relative to saidrail about an axis extending generally in a circumferential direction,pivoting said forearm relative to said upper arm in a plane containingthe upper arm and forearm, and pivoting the inspection head about panand tilt axes relative to said forearm.
 10. A method of inspecting insitu an interior of a transition piece body of one or more of aplurality of an annular array of combustors for a gas turbine,comprising the steps of: securing a mount of an interior roboticmanipulator to an open end of a combustion casing forwardly of one ofthe transition piece bodies, the manipulator having an elongatedinspection arm extending from said mount; locating an inspection headcarried adjacent an end of said inspection arm remote from said mountwithin the one transition piece body; manipulating said inspection armto locate said inspection head adjacent interior wall portions of theone transition piece body including by displacing the inspection head ina generally axial direction and generally radially toward a wall portionof the transition piece body to be inspected.
 11. A method according toclaim 10 including pivoting said arm about a pivot carried by said mountadjacent said open end of the combustion casing.
 12. A method accordingto claim 11 wherein the pivot comprises a universal joint, and the stepof displacing the inspection head toward the wall portion includesapplying forces to the inspection arm on a side of the mount remote fromthe inspection head wherein the applied forces have force components ina pair of right angularly related directions.
 13. A method according toclaim 12 including extending or retracting a pair of right angularlyrelated linear actuators coupled at opposite ends to said mount and saidarm, respectively.
 14. A method according to claim 10 including rotatingsaid inspection head about pan and tilt axes relative to said arm.
 15. Amethod of inspecting in situ side seam welds along a transition piecebody spaced inwardly of an impingement sleeve of a combustor in acombustion system for a gas turbine, comprising the steps of: providinga guide having a contoured surface generally corresponding to thecontour of the side seam weld of the transition piece body; fixing theguide to the combustor; and displacing an inspection head longitudinallyalong the space between the impingement sleeve and the transition piecebody so that the inspection head tracks the contoured surface of theguide whereby the inspection head is maintained during its longitudinaldisplacement in registration with the side seam weld of the transitionpiece body.
 16. A method according to claim 15 including adjusting thelocation of the inspection head relative to the guide and laterally ofthe weld.
 17. A method according to claim 15 including remotelyrecording the results from inspecting the weld.
 18. A method accordingto claim 15 including manually displacing the inspection headlongitudinally along the weld.